In general, for cultivation with soil and hydroponics in a greenhouse, at least half of the area of the greenhouse is used for a passage of workers during seeding, cultivation work, or harvest. Thus, there was a problem that as the area for cultivation reduces in half, production volume reduces, for which not only production costs but also consumer prices increase, resulting in an increase in cost burden of both producers and customers.
In order to solve these problems, the present applicant has filed Korean Patent Application No. 2016-0069465 covering a plant cultivation apparatus including: a driving unit 20 installed at trusses 12 horizontally crossing top portions of a greenhouse 10 and including a motor 21, a drive shaft 22, a plurality of driven shafts 24, and a plurality of worm gear reducers 23, a plurality of elevating units 30 including a plurality of main sprockets 31 axially fixed respectively to the plurality of driven shafts at regular intervals in a forward and backward direction, a chain 32 having a main part interlocking with the center of the main sprocket, a left part 32a directed downward from a left side of the main sprocket, and a right part 32b directed downward from a right side of the main sprocket, left and right supports 33 and 33′ whose top ends are vertically installed on the bottom of the truss to be spaced apart from the axially fixed position of the main sprocket at the same interval respectively, left and right guide sprockets 34 and 34′ axially installed at lower portions of the supports to be located at lower left and right positions than the main sprocket on which the left and right parts are hung downward, and cultivation gutters 40 and 40′ respectively ascending and descending in a state of being coupled to the left and right parts of the chain, as illustrated in FIGS. 1 to 3. Normally, a plurality of cultivation gutters is hung on the same horizontal line at the same height from the ground at regular intervals. When a passage of workers is required during seeding, cultivation work, or harvest, the plurality of elevating units raise and lower the left and right cultivation gutters alternately one by one by the operation of the driving unit to form a passage of workers between the raised cultivation gutters. Thus, the entire area of the greenhouse may be used as a cultivation area, so that the productivity may be double.
However, in order to raise and lower the left and right cultivation gutters 40 and 40′ alternately one by one by operating the plurality of elevating units 30 using one driving unit 20, the plant cultivation apparatus of the conventional earlier application includes the driving shat 22 rotatably installed by the motor 21, the plurality of driven shafts 24 installed perpendicular to the drive shaft, and the plurality of worn gear reducers 23 respectively installed at intersections of the drive shaft and the driven shafts and configured to simultaneously rotate the driven shafts by transferring a decelerated rotational force of the drive shaft thereto. Since the structure of operating a plurality of elevating members by transferring a driving force of the motor is complicated, a large number of parts are required, and installation time increases, installation and maintenance are very difficult and troublesome. Also, the cost burden of producers and customers cannot be reduced since there is a limit to lowering production costs because of rising costs for installation and maintenance and repair.